Evaluation of Cleft Adjacent Canine Eruption in Patients With Alveolar Cleft Treated With Early Secondary Alveolar Bone Grafting

Abstract

Objective

Evaluate cleft adjacent canine eruption in patients who underwent early secondary alveolar bone grafting (ABG).

Design

Retrospective cohort study.

Setting

North-American cleft center.

Subjects

A total of 121 children with nonsyndromic cleft lip and alveolus or cleft lip and palate (unilateral or bilateral).

Methods

Patients consecutively treated with early or later secondary ABG during a 10-year period were evaluated. The primary outcome identified the status of cleft adjacent canine eruption through the grafted site. Secondary outcomes included need for regrafting, need for pregraft expansion and status of the cleft lateral incisor. Categorical variables were compared with Pearson’s chi-square test and Fisher’s exact test, and P < .05 was considered statistically significant.

Results

A total of 152 ABG (125 early and 27 later ABG) were performed in 121 patients. The age at time of ABG differed significantly between the 2 groups with a mean age of 73.5 ± 5.0 months for the early ABG group versus 113.4 ± 32.0 months for the later ABG group (P < .001). None of the patients required pregraft expansion. The cleft diagnosis distribution was similar (P = .686). The overall need for regrafting was 1.3% and did not differ between the groups (1.6% vs 0%; P = .675). The cleft adjacent canine spontaneously erupted in 84.0% for early ABG versus 70.4% for later ABG group. Close to twice as many canines required surgical exposure (9.6% vs 18.5%) or extraction (6.4% vs 11.1%) in the later ABG group, but this difference was not statistically significant (P = .183).

Conclusions

Early secondary ABG, without pregraft expansion, does not compromise the eruption of the cleft adjacent canine compared to later secondary ABG.

Keywords

bone grafting cleft lip and palate cleft lip dental anomalies dental arch dental health dental occlusion nonsyndromic clefting orthodontics palatal expansion periodontal health tooth agenesis tooth development tooth movement

Introduction

Alveolar none grafting (ABG) is normally required in patients with cleft lip and alveolus (CLA) or cleft lip and palate (CLP) for the reconstruction of the alveolar cleft. Goals of alveolar bone grafts include providing sufficient bone stock for eruption and support of the cleft adjacent teeth; achieve closure of vestibular and palatal oral nasal fistulae; establish nasal skeletal base, floor of the nose and functional nasal airway; and provide adequate bone stock for the placement of a dental implant when the permanent lateral incisor is missing.¹

Later secondary ABG is typically performed in the mixed dentition before the maxillary canine eruption, from 8 to 11 years of age, when the canine root development is one-fourth to two-thirds of its final length.^2,3 The eruption of the cleft adjacent maxillary canine after later secondary ABG has been extensively studied, with canine impaction rate varying widely from 15.5%⁴ to 82%.⁵ Numerous factors have been hypothesized to affect the higher canine impaction rate in patients with CLP including the timing of surgery.^6-8

Early secondary ABG, before the eruption of the cleft side central incisor, has been advocated to optimize the periodontal status of all cleft-adjacent permanent teeth.¹ The approach has been shown to provide favorable bone stock^9,10 without compromising maxillary growth.^11-14 Limited studies to date have been published to assess definitive eruption of the cleft adjacent canines in the patients who underwent early secondary ABG. The mesio-distal position and angulation of erupting cleft adjacent canines in early secondary ABG has previously been evaluated as an indication for the risk for impaction, but the study did not assess the definitive eruption status of the canines, the need for surgical exposure, and how the ABG timing might affect the canine status.¹⁵

The aim of this study is to retrospectively evaluate cleft adjacent canine eruption in patients who underwent early secondary ABG (between 5 and 7 years of age) when compared to patients who underwent later secondary ABG.

Methods

This retrospective cohort study reviewed clinical records of patients with cleft lip and alveolus or cleft lip and palate (unilateral or bilateral), treated with early secondary ABG around 6 years of age or later secondary ABG at the IWK Health Center, Halifax, Canada, between January 2008 to January 2018. This study was approved by the IWK Health Center Research Ethics Board (IRB #1028728).

Secondary ABG was determined to be early if performed between the age of 5 and 7 (60-84 months) and later if performed after 7 years of age (after 84 months).

The inclusion criteria included patient with complete CLP (unilateral or bilateral), or CLA (unilateral or bilateral) treated with secondary alveolar bone grafting at the IWK Health Center and followed for a time frame sufficient to confirm clinically erupted cleft adjacent canine or active surgical-orthodontic exposure and eruption of the canine. The minimal age for inclusion in the study was 12 years.

The exclusion criteria for included patients with incomplete records, lost to follow-up, with congenitally absent cleft adjacent canine, and with insufficient follow-up or with congenitally missing canine teeth.

All the bone grafting procedures were completed by one of 2 surgeons. The protocol was developed and established by one of the surgeons and the identical procedure was used by both surgeons for all participants in the study¹ (Figure 1).

Figure 1.

Early secondary alveolar bone grafting in primary dentition prior to eruption of cleft adjacent central incisor. The white arrow shows the nasal floor reconstruction with cortical bone graft.

The primary outcome measure identified the status of the cleft adjacent canine tooth eruption through the grafted site (Figure 2). The cleft adjacent canine was determined to be:

self-erupted,

surgically exposed with bonding of orthodontic brackets, followed by active orthodontic canine eruption, or

extracted.

Figure 2.

Evolution of canine eruption after early alveolar bone grafting (ABG) (same patient as Figure 1).

Secondary outcomes measures assessed:

the need for regrafting,

the need for pregraft expansion,

the status of the cleft adjacent lateral incisor.

The lateral incisor was determined to either be present or absent. If present, its eruption or the need for surgical exposure or extraction was noted. The presence of supernumerary lateral incisors was also evaluated.

The primary and secondary outcomes were assessed based on previous radiographic imaging available in patient records along with recorded surgeon and orthodontic examination findings. Cleft diagnosis, age in months at time of ABG, alveolar bone graft complications and pathology associated with the cleft adjacent canine and/or lateral incisor were also recorded. The primary and secondary outcomes were compared between patients who had early and later secondary ABG.

Statistics

Statistical analysis was performed using the Statistical Package for Social Sciences software (SPSS.29.0, Chicago, IL). All variables were divided into continuous and categorical variables. Categorical variables were further subdivided into dichotomous and polychotomous variables. The Pearson’s χ² test and Fisher’s exact test were used to analyze 2 dichotomous or 2 polychotomous categorical variables, or a dichotomous categorical variable with a polychotomous categorical variable. The t test was used to evaluate a dichotomous categorical variable with a continuous variable. An analysis of variance (ANOVA) was chosen to analyze polychotomous categorical variables with continuous variables. For all statistical tests, a 95% confidence interval (CI) was used, and P < .05 was considered statistically significant.

Results

Over a 10-year period, a total of 152 ABG in 121 patients met the inclusion and exclusion criteria (Table 1). Two of the 152 ABG sites required regrafting for a total of 1.3% regraft; or 98.7% success rate. Both regraft sites involved one cleft site for a patient with BCLP. Timing of the ABG was not associated with the success rate/need to regraft (P = .675). None of the ABG sites required pregraft orthodontic expansion.

Table 1.

ABG Sites Included in the Study.

	Early ABG		Later ABG
Variables	N/Mean	%/SD	N/Mean	%/SD	P Value
ABG	125		27
Age (months)	73.5	5.0	113.4	32.0	<.001
Diagnosis					.686
UCLP	44	35.2%	9	33.3%
UCLA	24	19.2%	7	25.9%
BCLP	54	43.2%	10	37.0%
BCLA	3	2.4%	1	3.7%
Need for regrafting	2 ^a	1.6%	0	0%	.675
Pregraft expansion	0	0%	0	0%

Abbreviations: ABG, alveolar bone grafting; UCLP, unilateral cleft lip and palate; UCLA, unilateral cleft lip and alveolus; BCLP, bilateral cleft lip and palate; BCLA, bilateral cleft lip and alveolus.

Two regraft cases were one side of BCLP ABG.

The cleft adjacent canine erupted spontaneously in 124 ABG sites (81.6%), required surgically exposed in 17 ABG sites (11%), and required extraction in 11 ABG sites (7%) (Table 2).

Table 2.

Status of Cleft Adjacent Canine Tooth Eruption Through the Grafted Site.

	Early ABG		Later ABG
Variables	N	%	N	%	P Value
ABG	125		27
Canine					.183
Erupted	105	84.0%	19	70.4%
Surgical exposure	12	9.6%	5	18.5%
Extracted	8	6.4%	3	11.1%

Abbreviations: ABG, alveolar bone grafting; BCLP, bilateral cleft lip and palate.

Early secondary ABG was performed in 125 sites and later secondary ABG was performed in 27 sites (Table 1). The mean age at time of early secondary ABG was 73.5 ± 5.0 months versus 113.4 ± 32.0 months for later secondary ABG (P < .001). The cleft diagnosis between both groups did not differ significantly (p = .686). Complications occurred in 9 ABG sites (5.9%), including 5 postoperative infections, 1 dehiscence, and 3 residual oro-nasal fistula. An odontogenic cyst/enlarged dental follicle was diagnosed for 8 canines (5.3%) and 3 canines (2.0%) erupted in a transposed position (distal to the adjacent premolar). The cleft diagnosis did not have any significant effect on cleft adjacent canine eruption (p = .560), canine pathology (p = .529), or ABG complications (p = .403).

When comparing the early versus later ABG groups, close to twice as many canines required surgical exposure or extraction in the later ABG group; however, this difference was not statistically significant (Figure 3, Table 2, P = .183). The canine erupted spontaneously in 105 early ABG sites (84.0%) and in 19 later ABG sites (70.4%). The ABG timing did not have an impact on the rate of complication (P = .812), regrafting (P = 1.0) or canine pathology (P = .344).

Figure 3.

Percentage of cleft adjacent canine tooth eruption through the grafted site.

Cleft adjacent lateral incisors were absent in 48.8% (61) for the early ABG group and 44.4% (12) for the later ABG group (P = .627). A supernumerary lateral incisor was present in 6.4% (8) in the early ABG group and 0% (0) in the later ABG group. Lateral incisor eruption, need for surgical exposure of the lateral incisor, or need for extraction of the lateral incisor did not differ between the groups (P = .432). The presence or absence of a cleft adjacent lateral incisor did not have any significant impact on the cleft adjacent canine eruption (p = .290).

Discussion

Early secondary ABG, prior to the eruption of the cleft-adjacent maxillary central incisor, has been supported to promote the periodontal health of all cleft-adjacent permanent teeth,¹ and reliable bone sock,^9,10 without compromising maxillary growth.^11-14 This approach does not typically require presurgical orthodontic expansion, which could negatively impact the eventual canine eruption. This study showed that early secondary ABG around 6 years of age, without pregraft expansion, does not compromise the eruption of the cleft adjacent canine compared to patients treated with later secondary ABG.

The timing of alveolar bone graft surgery has been hypothesized to affect the canine impaction rate in patients with CLP.^6-8 This study has demonstrated that an earlier secondary ABG did not negatively impact the eruption of the cleft adjacent canine, with close to twice as many canines requiring surgical exposure or extraction when later secondary ABG is performed (P = .183). Even though the difference is not statistically significant, in this case there is a clinically significant difference with twice the number of canines requiring either surgical exposure or extraction. The results must be assessed statistically but furthermore also from a clinical perspective and what we might discuss with patients. With no demonstrated negative effects, twice the risk for exposure or extraction becomes clinically significant. Other studies have also reported similar findings.^8,15-17 Kleinpoort et al⁸ retrospectively evaluated 60 patients with UCLP and found that the canine impaction risk at the age of 10 was 14.29% (4/28) with early secondary bone grafting at 6 years of age and 21.88% (7/32) without early secondary grafting at 9 to 11 years of age (P = .45). Similarly, cone beam computed tomography (CBCT) found no difference in canine eruption path between the younger (< 9 years) and older (> 9 years) children with CLP treated with secondary ABG.¹⁶ Hoang et al¹⁷ also found no significant difference in frequency of canine impaction by stage of root development and no association between age at first graft and frequency of canine impaction after evaluating ABG in 257 patients with cleft.

The secondary ABG technique used in this study was highly predictable with a 98.7% success rate, and a 1.3% rate of regraft. This compared favorably to other similar studies reporting rates of graft failure varying between 6.3% and 11.8%.^17-19 In our study, the timing of the secondary ABG did not influence the graft success (P = .675), this also being reported by other studies.^8,16 However, other studies have shown that early secondary ABG provides a better success rate compared to later secondary ABG.^20-22 Kortebein et al²¹ found that early secondary ABG performed at 5 to 7 years of age was associated with a higher graft success rate (97.2%) compared to later secondary ABG at 8 to 11 (92.5%), 12 to 15 (90.5%), and 16 (58.3%) years of age (P = .025). Residual bone volume evaluated with CBCT 6 months postoperatively was also found to be significantly increased in patient treated with early secondary ABG compared to later secondary ABG (P = .012).²² The osteoinductive properties of the erupting central and/or lateral incisor in the grafted bone have been hypothesized to be related to the better bone formation and reduced resorption.^20,21,23

None of the secondary ABG performed in this study required pregraft expansion confirming that orthodontic expansion is not typically required to obtain successful ABG. Due to this, the effect of pregraft expansion on the rate of canine impaction could not be evaluated. Other studies have shown that pregraft expansion does not influence the rate of canine impaction.^17,24 Hoang et al¹⁷ evaluated factors contributing to canine impaction in 257 patients with cleft undergoing secondary ABG and found that pregraft expansion did not influence significantly the rate of canine impaction, with canines being impacted in 32.5% with expansion versus 22.9% without expansion (P = .063). In this study, the most significant factor leading to a canine impaction was the absence of the primary canine at the time of the ABG (P = .02).¹⁷

In this study, the presence or absence of a cleft adjacent lateral incisor did not impact the canine eruption (P = .290). The timing of ABG did not influence the rate of lateral incisor eruption, surgical exposure, or extraction (p = .432). Many studies have also found no significant association between the presence or absence of lateral incisors and canine impaction.^17,24-26 Other studies have reported a correlation between impacted canines and missing lateral incisors on the cleft side, suggesting that the presence of the lateral incisor may guide the eruption of the canine through the grafted alveolus.^15,24,27 It has also been suggested that the presence of supernumerary lateral incisors increase the need for surgical orthodontic traction.²⁶ The influence of the lateral incisor remains unclear and may be a contributory factor but not a determining factor. This aspect requires further investigation.

The main study limitations included the retrospective design and associated biases and the smaller sample size of the later ABG group. In addition, the ABG success rate was established on the need for regrafting which was based on clinical radiographic findings. Although questionable bone grafts were evaluated further with CBCT, not all patients in this study received a postoperative CBCT. This could have overestimated our bone graft success rate, especially since other studies have reported 30% to 40% success rates when evaluating ABG with CBCT.^28-30 There were however no identified issues with the bone present in the cleft site when subsequent orthodontic treatment occurred. Future studies with larger sample sizes and three-dimensional imaging such as CBCT are needed to better identify factors contributing to canine impaction and successful graft integration.

Conclusions

Early secondary ABG prior to the eruption of the central incisor, does not compromise the eruption of the cleft adjacent canine when compared to later secondary ABG. The presented bone grafting technique is highly successful and does not require pregraft expansion. The presence or absence of a cleft adjacent lateral incisor did not appear to be a factor influencing canine eruption. Further controlled prospective studies with three-dimensional imaging are needed to confirm these findings.

Footnotes

Authors’ Note

This article was presented, in part, at the American Cleft Palate–Craniofacial Association 2024 annual meeting in Denver, CO, April 2024.

ORCID iDs

Jean-Charles Doucet

Manan Harshadray Patel

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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